Power generating or other plants circulate fluids, such as water or steam, through tubes or banks of tubes. The fluid is often heated and used, for example, to drive turbines which generate electricity.
The tubes are generally arranged in large panels or banks of parallel tubes which are connected together with a metal membrane or web continuously interposed between each pair of adjacent tubes in the bank to form a tube wall. The tubes generally have an outer diameter which can range from about 1 inch up to about 3 inches, with a wall thickness which can be up to about 0.5 inch. On account of deterioration due to corrosion and the like, the tubes occasionally require replacement. Ordinarily, repair of damaged or worn tubing involves cutting and removal of relatively large sections of the tube banks, and replacement with a new panel of tubes. The bank sections are generally replaced in large rectangular sections typically having sizes ranging from a few feet to 10, 20, 100 or even 200 feet in length.
Tube wall sections are generally removed by using either hand held tools such as motor driven saws or cutting torches, or more desirably by using various track mounted cutting apparatuses.
A portable tube cutting apparatus having a vice-like fastener for supporting the apparatus from a stationary object, such as the tube which is to be cut, is disclosed in U.S. Pat. No. 5,199,221. The disclosed apparatus can be used to cut the tube which supports the apparatus as well as other adjacent tubes in close proximity.
A track mounted cutting apparatus is disclosed in U.S. Pat. No. 5,582,538. The portable tube cutting apparatus which facilitates smooth, even cuts through a boiler tube wall includes a frame supporting a movable carriage adapted for movement in a linear direction relative to a frame which has articulated support means for securing the device to a boiler tube wall.
These prior art devices have utilized various means for securement of the carriage against the boiler tube wall to prevent lateral movement of the cutting apparatus once the position at which cutting will proceed has been achieved. The devices have an inherent drawback, however, in that they require some form of brake mechanism in addition to the other components of the pipe cutting assembly.
It would, therefore, be desirable to provide a securement mechanism which prevents the lateral movement of a pipe cutting assembly along a tube wall without the necessity of additional mechanical brake components to the apparatus.